66 College of Forestry 
(p. 82) and it has been pointed out that of these all but 
Eurytoma sp. are probably parasitic upon P. dimidiatus. 
Asemum moestum Hald. 
Asemum moestum has been recorded from Canada south- 
ward to Florida. It is known from Lake Superior and 
Packard (1890, pp. 697) has taken it from Colorado and 
states that it undoubtedly breeds in coniferous trees in the 
Rocky Mountain region. LeConte believes that it occurs in 
Alaska (Packard, 1890, pp. 697). The host trees include 
white pine (Packard, 1890, pp. 697), yellow pine and spruce 
(Hopkins, 1899, pp. 438). Apparently larch has never 
been recorded as a host, but it is likely that this borer will 
be found in a large number of coniferous trees throughout 
its range. 
This beetle lives in the larval stage in the base of the 
trunk. We have never bred it from wood more than a few 
feet from the ground. It is then, as will be readily seen, 
most often found in the stumps of its host trees in regions 
which are being lumbered. The adults will apparently 
deposit their eggs only in green, sappy material, and our 
observations show that it very often enters the larch even 
before this shows any visible signs of weakness — sometimes 
a full year before the entrance of Dentroctonus. 
The young larve on hatching burrow into the sapwood 
and often extend their mines deep into the heartwood. These 
mines, which are somewhat flattened in cross section, are 
more or less winding in their course, but with ‘the general 
direction more usually longitudinal. The larve are often 
very numerous, in one case six larvee of various sizes being 
taken from a space about six inches square. This beetle 
ordinarily requires two years to complete its larval growth 
and the probabilities are that occasionally a longer time is 
necessary. The pupal stage is passed in an enlarged cham- 
ber at the end of the larval burrows. This is constructed 
in the sapwood quite close to the bark. The adult emerges 
through an oval hole in the bark. Beetles emerged from 
larch May 29 and June 15, 1916. Numerous other adults 
